View clinical trials related to Healthy Volunteers.
Filter by:Background: - By the time diseases of the retina are detected, serious damage has often already been done. Researchers want to find better ways of viewing the retina. One way called adaptive optics may help detect problems earlier. Objectives: - To study if adaptive optics can help find better ways to diagnose, treat, and manage retinal diseases. Eligibility: - People over age 12 with an eye disease. - Healthy volunteers over age 12. Design: - Participants will be screened with medical history and eye exams. These may include dilating pupils and taking pictures of the eyes. - Participants will have 1 or more study visits. They will have: - Medical and eye history. - Questions about their medications. - Eye exam including pupil dilation. - Adaptive optics imaging. After dilation, participants sit still while looking into an adaptive optics instrument. They look at specific places and images are taken of their retina. - They may also have: - More images. - Perimetry. Participants look into a lens and press a button when they see a light. - Color vision tests. - Electroretinogram. Participants will get numbing eye drops and special contact lenses. A small metal electrode will be put on their forehead. They will look at flashing lights and try not to blink.
During operations to treat abdominal problems the blood pressure can fall, resulting in falls in blood flow to the vital organs. This fall can be treated by the administration of drugs that cause constriction of blood vessels. Although these drugs correct falls in blood pressure, it is unclear what effect they have on blood flow from the heart and to the vital organs. In this study of healthy volunteers we aim to better understand the changes in blood flow in both small and large vessels that occur in response to administration of these drugs. To do this we will use two different techniques of ultrasound imaging. A narrow (4-5mm) ultrasound probe will be inserted into the oesophagus via a nostril to measure blood flow in a major blood vessel. A second probe will rest on the abdomen and will record changes in blood flow in small vessels of the liver. Two drugs which raise the blood pressure via different mechanisms will be administered and the changes in flow from the heart and to vital organs will be measured and compared.
This study is designed to evaluate the bioequivalence of the two treatments, the administration of CJ-30059 and the co-administration of candesartan cilexetil and amlodipine besylate, in healthy volunteers.
Background: Type 2 diabetes mellitus is a main risk factor for cardiovascular disease and heart failure, in part due to diabetic cardiomyopathy. However, the association between intracellular lipid accumulation and (myocardial) functional impairment is likely more complex than originally imagined. Recent studies suggest that not fat per se, but the content of saturated or unsaturated fatty acids might predict the development of cardiac steatosis and myocardial dysfunction. In addition skeletal muscle and hepatic glycogen metabolism is impaired in patients with diabetes mellitus. Data from animal experiments suggest a relevant role of myocardial glycogen stores in ischemic preconditioning. Due to methodological limitations so far data on myocardial glycogen stores and myocardial lipid composition in humans are missing. Hypothesis: In addition to total ectopic lipid deposition in the myocardium, myocardial lipid composition, i.e. the relative abundance of saturated and unsaturated fatty acids, and impaired myocardial glycogen metabolism may play an important role in the development cardiac lipotoxicity leading to diabetic cardiomyopathy. Pancreatic endocrine function and myocardial morphology and function is altered in patients with heterozygote inactivating mutations of the CaSR-gene / FHH. Aims: - Metabolic virtual biopsy of the myocardium for identification of specific patterns of intracellular lipid composition and myocardial glycogen metabolism as possible critical determinants of metabolic cardiomyopathy - Characterization of the metabolic interplay between the myocardium, skeletal muscle, liver and adipose tissues in different stages of development of type 2 diabetes compared to patients with calcium sensing receptor mutation Methods: - 1H/13C and 31P magnetic resonance spectroscopy and imaging for measurements of myocardial, skeletal and liver lipid and glycogen content, abdominal adipose tissue distribution and composition, ATP synthesis and myocardial functional parameters - Mixed meal tolerance tests to trace the postprandial partitioning of substrates between insulin sensitive tissues (myocardium, skeletal muscle, liver, adipose tissue). - Hyperinsulinemic-hyperglycemic glucose clamp (HHC) with enrichment of the infused glucose with the stable isotope [1-13C]glucose to trace the incorporation of circulating glucose into myocardial glycogen in healthy insulin sensitive volunteers, prediabetic insulin resistant volunteers with impaired glucose tolerance, healthy subjects, patients suffering from type 2 diabetes mellitus, patients suffering from type 1 diabetes and patients with heterozygote mutation in calcium sensing receptor.
The use of lasers in medicine in general, and diagnosis and treatment in ophthalmology in particular, increased significantly. Making retinal surgery using lasers have become increasingly common. The goal: to diagnose eye diseases safely
The purpose of this study is to see if an enzyme in the body (5-alpha reductase, 5αR) is important in controlling how the body handles sugar and fat. The investigators believe that 5αR is a crucial step in regulating these actions as well as controlling how insulin works in the body but regulating the amount of steroid hormones including cortisol and testosterone in the body. In previous clinical studies, the investigators have shown that the activity of 5αR increases as you gain weight and decreases with weight loss. In addition, work that the investigators have performed in the laboratory has shown that if you increase 5αR levels in liver cell grown in the laboratory, the amount of fat that they contain increases. The investigators would therefore like to demonstrate the effect of inhibition 5αR on the regulation of insulin, glucose and fat in the body.
Objective: In this study we will develop and apply imaging techniques to perform the first three-dimensional (3-D) measurements of brain biomechanics during mild head movement in healthy human subjects. Biomechanics is the application of mechanics, or the physical principles in action when force is applied to an object, to the anatomical structure and/or function of organisms. Such techniques will be invaluable for building computational models of brain biomechanics, understanding variability of brain biomechanics across individual characteristics, such as age and sex, and determining brain sub-structures at risk for damage when movement of the head is accelerated, such as during a traumatic event. Study Population: Measurements will be performed on 90 healthy men and women aged 18-65. Design: We will build upon the model pioneered by our collaborator, Dr. Philip Bayly. The model places a human subject in a magnetic resonance (MR) scanner with one of two head support units that allows a specific range of motion. Each head support is latched such that it can be released by the subject, and results in either a rotation of the head of approximately 30 degrees or a flexion-extension of the head of approximately 4 degrees. Although both supports are weighted so that the motion is repeatable if the subject is relaxed, the subject can easily counteract the weight. The resulting acceleration/deceleration is small (in the range of normal activities, such as turning one's head during swimming) and has been validated and used in other human investigations of brain biomechanics. The subject repeats the motion multiple times during the MR scan under their own volition and desired pace to measure motion of the head and brain. Outcome measures: This project is a pilot study evaluating the potential of extracting three-dimensional estimates of brain deformation, such as strain measurements, using MR imaging. A primary outcome of this project will be a fast MR acquisition sequence for measuring 3-D brain deformation. The sequence will be evaluated by applying the protocol to human subjects, followed by preliminary quantification of the reproducibility and stability of deformation measurements.
Background: - Researchers at the National Institutes of Health give many tests of hearing and balance. These tests can help detect problems that affect hearing or balance. It is important to know exactly how healthy people perform on each of these tests. This information will indicate when a test result is normal and when a test result shows a problem. Researchers also want to determine the best methods for each test. Objectives: - To test different types of hearing and balance tests, and collect information on normal values for each test. Eligibility: - Healthy volunteers between 5 and 70 years of age. Design: - This study will require a single visit to the National Institutes of Health Clinical Center. It will include both screening tests and study tests of hearing and balance. Sometimes, a second visit may be required if a test is designed to measure the same thing on 2 different days. Each visit will last between 2 and 5 hours, depending on the number of tests scheduled per visit. - Participants will have a physical exam and medical history. They will also have basic tests to check for normal hearing and balance. - Participants may have different hearing tests, including the following: - Auditory Evoked Potentials to study how the ears and brain handle sound information. - Auditory Processing Tests to study how a person processes complex sounds like speech in background noise. - Tests of middle ear and inner ear function. - Participants may have different balance and inner ear tests, including the following: - Balance test on a tilting platform. - Different tests to measure how well the eyes, ears, and brain work together to help maintain balance. - Treatment will not be needed as part of this study.
Background: - Gum disease is a condition in which the tissue around the tooth root becomes swollen and infected. This condition can cause tooth loss if it is not treated. Who gets gum disease and how bad it will be depends on (1) the different bacteria in the mouth and (2) how the immune system of an individual handles these bacteria. Researchers want to look at the oral bacteria and genetic immune problems of different people to learn how these affect gum disease and other conditions of the mouth. Objectives: - To study how immune system problems may lead to problems in the mouth, including gum disease. Eligibility: - Children and adults at least 7 years of age who have genetic problems with their immune system. - Healthy adults that have periodontal disease - Health adults that do not have periodontal disease Design: - This study will involve a screening visit and a study visit. - Participants will be screened with a medical history, blood work and a full oral and dental exam, including dental x-rays and photos. - The study visit will involve collection of blood, urine, and other samples, including saliva, plaque, and gum swabs. Any abnormal tissue will sampled for a biopsy. Additional oral and dental exams will be performed. Participants will also answer questions about any current medical or dental problems.
Background: - Imaging tests, such as magnetic resonance imaging (MRI), can provide information about heart and blood vessels. The tests let doctors can see the amount of blood vessel narrowing and vessel wall thickness. This information may help diagnose and treat heart disease and other conditions that lead to heart attacks. Better MRI methods are needed to improve heart disease diagnosis, especially by avoiding the use of radiation. Researchers are testing new techniques to improve the quality of heart MRI, compared with more complex studies like catheterization or angiography. Objectives: - To compare heart MRI techniques with other tests used to diagnose heart disease. Eligibility: - People at least 18 years of age who either have or may have heart disease, or are healthy volunteers. Design: - Participants will be screened with a physical exam, medical history, and blood tests. - They will have an angiography to study the inside of blood vessels. This test is an x-ray study of the blood vessels. It will be done either separately or as part of a set of tests to diagnose possible heart disease. - Participants will have at least one and up to five MRI scans. The scans will involve different methods of studying the heart and blood vessels. Participants may also have a computed tomography scan to confirm the findings of an MRI scan. - No treatment will be provided as part of this protocol.